Fill system and method including visual indicator device for empty condition

ABSTRACT

A fill system is configured to supply particulate adhesive such as pellets to an adhesive dispensing system and is configured to provide a visual indication when a supply container approaches an empty condition. The fill system includes the supply container, which has an interior space for holding pellets, and an indicator device that emits a visual indication by actuating a light source communicating with the interior space. As a result, when the level of pellets within the interior space drops to a threshold approaching the empty condition, the light energy emitted by the indicator device is visible outside the supply container. The fill system may then be refilled before the completely empty condition is reached.

FIELD OF THE INVENTION

The present invention generally relates to particulate material fillingsystems and more particularly, to an adhesive pellet filling system andmethod used with adhesive dispensing systems.

BACKGROUND

A conventional dispensing system for supplying heated adhesive (i.e., ahot-melt adhesive dispensing system) generally includes a melter havingan inlet for receiving adhesive materials in solid or liquid form, aheater grid or cartridge for heating the adhesive materials, an outletfor receiving the heated adhesive, and a pump in communication with theoutlet for driving and controlling the dispensation of the heatedadhesive through the outlet. One or more hoses may also be connected tothe outlet to direct the dispensation of heated adhesive to adhesivedispensing guns or modules located downstream from the melter.Furthermore, conventional dispensing systems generally include acontroller (e.g., a processor and a memory) and input controlselectrically connected to the controller to provide a user interfacewith the dispensing system. The controller is in communication with thepump, heater grid or cartridge, and/or other components of the system,such that the controller controls the heating/melting and dispensationof the heated adhesive.

In dispensing systems including a melter supplied with solid material,the solid particulate adhesive material may be provided on demand to themelter in the form of adhesive pellets. These adhesive pellets may besupplied into the melter using various techniques, includinghand-filling or automated filling, depending on the specific design ofthe melter. Some melters are designed in such a manner that hand fillingis not possible. In some of these systems, the adhesive pellets aredesigned to be transferred by pressurized air from a fill system intothe melter, when the melter requires additional material to heat anddispense. In this regard, the controller operatively connected to themelter can receive signals indicating the amount of adhesive material inthe melter and then actuate delivery of more pellets from the fillsystem when the amount of adhesive material in the melter is low. Thefill system therefore ensures that the amount of adhesive materialwithin the melter remains at sufficient levels during operation of thedispensing system.

One particular type of fill system is a tote-based pneumatic fill systemused to provide adhesive pellets to a melter. The tote-based pneumaticfill system includes a supply container (which may also be referred toas a tote) with an interior space having a size sufficient to holdenough adhesive material for multiple hours of operation of thedispensing system. As a result, the fill system typically only has to berefilled with adhesive pellets once a day or once per operational shift,in some circumstances. The lengthy time periods between refillingoperations of the supply container can sometimes lead to operatorsforgetting to check whether the fill system is getting close to empty.In addition, the level of pellets within the supply container drops at aslow pace during normal operation, so it can be difficult to gauge howmuch material is left in the supply container, and when the supplycontainer will need to be refilled. These problems of detecting thelevel of pellets within the supply container are particularlyexacerbated when the pellet level is only checked by an operator openinga lid at the top of the supply container and looking down into thesupply container. If the supply container of the fill system runs out ofadhesive material, operation of the dispensing system must be shut downuntil the supply container can be refilled. This refilling process andthe resulting restart process for the dispensing system can causesignificant downtime if the empty condition of the supply container isnot anticipated and addressed in advance of the supply containerreaching the empty condition.

For reasons such as these, an improved fill system would be desirablefor use with dispensing systems.

SUMMARY OF THE INVENTION

According to one embodiment of the invention, a fill system configuredto supply particulate adhesive to an adhesive dispensing system includesa supply container having an interior space for receiving theparticulate adhesive and defined by at least one sidewall and a bottom.The at least one sidewall includes at least a portion defined bytranslucent or transparent material. The fill system also includes anindicator device for emitting a visual indication when the supplycontainer is approaching an empty condition. The indicator device has atleast one light source communicating with the interior space such thatlight energy is emitted in the interior space so as to be visiblethrough the translucent or transparent material to an operator when thesupply container is approaching the empty condition.

In one aspect, the supply container also includes a window defined bythe translucent or transparent material at the sidewall. As a result,the light energy emitted by the indicator device is visible through thewindow at the exterior of the supply container when the supply containeris approaching the empty condition. This visual indication is thereforeprovided without requiring an operator to open the lid of the supplycontainer. The light source may emit light energy throughout theinterior space such that a majority of the supply container lights upwith internal illumination when the supply container approaches theempty condition.

In another aspect, the light source is mounted at least partially inadditional structures located within the interior space. To this end,the additional structures are already present in the interior space andso the addition of the light source provides minimized additionalresistance to the flow of particulate adhesive towards the bottom of theinterior space. One type of structure already located within theinterior space is a venturi pump housing of a pump configured toselectively remove particulate adhesive from the interior space. Inthese embodiments, the light source is mounted at least partially withinthe venturi pump housing. It is also possible for the drivers or otherelectronics associated with the light source to be housed within thepump housing, thereby minimizing more space required by the indicatordevice.

The light source may be mounted in various locations within or adjacentto the interior space of the supply container. For example, the lightsource may be mounted on or adjacent to a ramp located at the interiorspace and configured to direct gravity-driven flow of particulateadhesive towards the bottom of the interior space. The ramp may bepainted with a color contrasting to the particulate adhesive or to thelight energy emitted by the light source to thereby increase thevisibility of the visual indication. Thus, the light source may becoupled to the ramp so as to be located within the interior space, orthe light source may be positioned behind a ramp aperture in the ramp sothat the light source is not within the interior space yet still emitslight energy into the interior space via the ramp aperture. Thispositioning behind the ramp and outside the interior space may bepreferred if it is desired to minimize the impedance to the flow ofparticulate adhesive within the interior space.

In yet another aspect, the indicator device includes a plurality oflight sources that are positioned to emit light energy in differentdirections within the interior space. Such mounting of a plurality oflight sources will ensure that some light energy is transmittedthroughout the interior space regardless of whether the piling ofparticulate adhesive within the supply container takes a differentformation during different operational cycles. The plurality of lightsources may alternatively be positioned in a series located along anelongate length of the ramp. In these embodiments, the series of lightsources will be sequentially uncovered as the supply containerapproaches the empty condition, thereby increasing the intensity oflight energy within the interior space as the supply containerapproaches the empty condition. The indicator device may include firstand second portions of light sources, with the first portion configuredto emit a different color or intensity of light energy compared to thesecond portion. In these embodiments, the first portion of light sourcesis positioned to be uncovered before the second portion of light sourcessuch that the difference in color or intensity can be used to indicatehow close the supply container is to the empty condition.

In still another aspect, the light source emits light energy in aflashing pattern. This flashing pattern causes the light energy to beinitially detected as a pulsing light energy through the particulateadhesive when the light source is nearly uncovered, and then laterdetected as a flashing light energy when the light source is uncovered.The light source may be a rugged light emitting diode that is resistantto high temperatures and other environmental conditions typical at thesupply container. The light source may be positioned within the supplycontainer such that the light source is uncovered when the particulateadhesive in the interior space has emptied to a selected fill percentagewithin the range of about 2% filled to about 25% filled. Even morepreferably, the light source may be positioned to be uncovered when theparticulate adhesive in the interior space has emptied to a selectedfill percentage within the range of about 2% filled to about 10% filled.This amount of fill percentage generally provides adequate time for anoperator to notice the visual indication and then refill the supplycontainer before the supply container runs out of particulate adhesive.

In another embodiment according to the invention, a method of supplyingparticulate adhesive to an adhesive dispensing system includes receivingparticulate adhesive within an interior space of a supply container. Themethod also includes removing particulate adhesive from the interiorspace of the supply container to supply the particulate adhesive to theadhesive dispensing system. A light source is illuminated such thatlight energy is emitted by the light source in the interior space whenthe supply container is approaching an empty condition. The supplycontainer includes a sidewall with at least a portion defined bytranslucent or transparent material, and the emission of light energy inthe interior space is visible through the translucent or transparentmaterial to provide a visual indication detectable by an operatoroutside the supply container. Therefore, the supply container can berefilled before reaching the empty condition.

These and other objects and advantages of the invention will become morereadily apparent during the following detailed description taken inconjunction with the drawings herein.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute apart of this specification, illustrate embodiments of the invention and,together with a general description of the invention given above, andthe detailed description of the embodiments given below, serve toexplain the principles of the invention.

FIG. 1 is a schematic view of an adhesive dispensing system, including afill system having a supply container according to one embodiment of thecurrent invention.

FIG. 2 is a perspective view of the fill system of FIG. 1, with aportion of the supply container cut away to show a pump and an indicatordevice located along a ramp.

FIG. 3 is a front perspective view of the ramp of FIG. 2, specificallyshowing the portions of the pump and the indicator device located withinthe supply container.

FIG. 4 is a cross-sectional side view of the fill system of FIG. 2,specifically illustrating components located behind the ramp.

FIG. 5 is a perspective view of a lower portion of the pump of FIG. 3.

FIG. 6 is a cross-sectional view through the pump of FIG. 5 along line6-6, to illustrate the mounting of one or more LEDs within the pumphousing.

FIG. 7 is a perspective view of another embodiment of the lower portionof the pump of FIG. 3, including a series of LEDs positioned along thelength of the pump housing.

FIG. 8 is a cross-sectional side view of another embodiment of the fillsystem with different mounting arrangements for LEDs within the supplycontainer.

FIG. 9 is a schematic cross-sectional side view of the fill systemaccording to the invention including a supply container filled with ahigh amount of pellets, thereby blocking light energy from being emittedthrough the pellets as shown.

FIG. 10 is a schematic cross-sectional side view of the fill system ofFIG. 9, with the pellet level within the supply container lowered suchthat a minimum amount of light energy is emitted through the pellets.

FIG. 11 is a schematic cross-sectional side view of the fill system ofFIG. 10, with the pellet level within the supply container lowered belowthe LED such that the light emitted inside the supply container is at ahigher intensity than in FIG. 10.

DETAILED DESCRIPTION OF THE ILLUSTRATIVE EMBODIMENTS

Referring to FIG. 1, an adhesive dispensing system 10 in accordance withone embodiment of the invention includes a fill system 12 that isconfigured to provide a visual indication when the particulate adhesivewithin a supply container 14 is approaching an empty condition. Morespecifically, the fill system 12 is used to provide adhesive pellets toa melter 16 of the adhesive dispensing system 10, and the melter 16feeds liquefied molten adhesive to an applicator module or nozzle 18using a liquid pump 20. In this regard, the fill system 12 is operatedto continually replenish the supply of adhesive within the melter 16 asthe pump 18 removes molten adhesive for dispensing at the applicatormodule or nozzle 18. The adhesive material may define any form or shapethat is convenient for delivering by the fill system 12 and for meltingby the adhesive melter 16; however, “pellets” have been chosen forillustrative purposes in the illustrated embodiment. It will beunderstood that the material moved by the fill system 12 may defineother solid or semi-solid particulate forms and may consist ofnon-adhesive materials in other embodiments consistent with theinvention. The supply container 14 of the fill system 12 can hold asignificant amount of pellets of adhesive such that the fill system 12only needs to be refilled or serviced by an operator every few hours, oron another relatively infrequent basis. However, the provision of anindicator device in the form of one or more light emitting diodes (LEDs)22 causes the emission of light energy in the supply container 14, whichcan be detected when the supply container 14 approaches an emptycondition. The supply container 14 may then be refilled before beingcompletely empty, which enables continuous operation of the adhesivedispensing system 10 without significant downtime, when continuousoperation is desirable. Furthermore, this indicator device may alsoavoid the use of active level sensors that would add more expense to thefill system 12 while also requiring additional maintenance.

With continued reference to FIG. 1, the adhesive dispensing system 10may also include a controller 24 that is operatively connected to themelter 16 and to the fill system 12. The controller 24 receives signalsfrom a level sensor or some other monitoring device within the melter 16that correspond to the amount of adhesive within the melter 16. When theamount of adhesive within the melter 16 drops below a certain threshold,the controller 24 sends another signal to the fill system 12 to actuatedelivery of an amount of pellets into the melter 16 to refill the melter16. For example, the fill system 12 may include an outlet port 26connected to a hose 28 extending between the supply container 14 and themelter 16. The delivery of the pellets through the outlet port 26 andthe hose 28 may be produced with pressurized air, as well understood inthe filling and dispensing field. However, it will be understood thatthe pellets in the supply container 14 may be removed in otherembodiments using other known methods including mechanical agitators andsimple gravity flow. The control process for periodically refilling themelter 16 continues as long as the melter 16 is operating so that themelter 16 (and subsequently, the applicator module or nozzle 18) neverruns out of adhesive material. It will be understood that the controller24 may be incorporated into one or more control systems (not shown) thatalso actuate the liquid pump 20 and the applicator module or nozzle 18in accordance with external or pre-programmed control signals, withoutdeparting from the embodiments of the invention.

The fill system 12 may be used with various types of adhesive dispensingsystems 10. In one example, the melter 16, liquid pump 20, andapplicator module or nozzle 18 may include a wall-mounted melt assemblyas described in U.S. Patent Application No. 61/703,454 to Clark et al.(entitled “Adhesive Dispensing Device Having Melt Subassembly withOptimized Reservoir and Capacitive Level Sensor”), which is co-owned bythe assignee of the current application and the disclosure of which ishereby incorporated by reference herein in its entirety. However, itwill be understood that the fill system 12 is designed for use with anytype of adhesive dispensing system requiring periodic refilling ofmaterial without departing from the scope of the invention. Moreover,the fill system 12 may be modified by including the indicator devicewith other types of supply containers in other embodiments of theinvention.

FIGS. 2 through 6 illustrate one embodiment of the fill system 12 inaccordance with the invention. The fill system 12 includes theaforementioned supply container 14, which defines a tote having theappearance similar to that of a wheeled waste container. Morespecifically, the supply container 14 includes a main container body 32defined by a plurality of sidewalls 34 and a bottom wall 36. In theillustrated embodiment, the plurality of sidewalls 34 includes foursidewalls 34 that define a rectangular-shaped main container body 32.The main container body 32 is closed at a top end 38 by a removable lid40 that may be pivotally coupled to one of the sidewalls 34 as shown inFIG. 2. An interior space 42 for holding pellets of adhesive is definedby the sidewalls 34, the bottom wall 36, and the lid 40 of the supplycontainer 14. In order to refill this interior space 42, the lid 40 maybe pivoted open so that a new supply of pellets can be deliveredmanually or automatically through the top end 38. The supply container14 of this embodiment also includes wheels 44 coupled to the maincontainer body 32 adjacent the bottom wall 36 so that the supplycontainer 14 can be repositioned easily during operation and forrefilling. Although it will be appreciated that the specific structuredefining the shape of the supply container 14 and the interior space 42may be varied in other embodiments consistent with the invention, theinterior space 42 is always sized to contain a significant amount ofadhesive material so that the fill system 12 requires refilling on aninfrequent basis.

The supply container 14 shown in FIG. 2 also includes windows 46 locatedin three of the sidewalls 34. The windows 46 are formed from atransparent or translucent material that enables light energy to betransmitted from the interior space 42 by the indicator device, asdescribed in further detail below. Alternatively, the sidewalls 34 mayinclude at least a portion defined by a transparent or translucentmaterial without the provision of windows in other embodiments. Anoperator may view a fill level of pellets (not shown in FIG. 2) throughthe windows 46 during emptying of the supply container 14; however, thisprocess of monitoring the fill level of pellets is similar to openingthe lid 40 and looking down into the interior space 42, both of whichare relatively inaccurate ways to determine the amount of pelletsremaining in the supply container 14. Therefore, as described in furtherdetail below, the LED 22 mounted at the supply container 14 ispositioned to emit light energy in the interior space 42 and through thetranslucent or transparent material of the windows 46 when the supplycontainer 14 approaches an empty condition, thereby drawing attention tothe need to refill the supply container 14. It will be appreciated thata different number of windows 46, including no windows 46 at all, may beprovided in the sidewalls 34 in other embodiments of the invention.

The supply container 14 also includes a ramp 48 positioned along one ofthe sidewalls 34. The ramp 48 is configured to support a pump 50configured to remove pellets from the interior space 42 when pelletsneed to be delivered to the melter 16. In the embodiment shown in FIGS.2 and 3, the ramp 48 is inserted into the interior space 42 through acutout portion of a rear sidewall 34 adjacent the wheels 44 or throughthe top end 38 and then positioned along the rear sidewall 34 so thatthe interior space 42 tapers downwardly towards the bottom wall 36. Theramp 48 thereby directs gravity flow of pellets to a relatively smallarea at the bottom wall 36. The pump 50 includes a pump conduit 52mounted along the ramp 48 and having an inlet 54 located to adjacentthis relatively small area at the bottom wall 36. The pump conduit 52extends to the outlet port 26, which is located along the rear sidewall34. Accordingly, the pump 50 draws gravity-fed pellets of adhesive intothe inlet 54 from the bottom of the interior space 42 so that the supplycontainer 14 continues to operate until the interior space 42 issubstantially emptied of pellets. As will be readily understood, thepump 50 may be replaced with alternative structure for removing adhesivepellets from the interior space 42 in other embodiments, including butnot limited to mechanical agitators.

With particular reference to FIGS. 3 and 4, further details of the ramp48 and pump 50 are shown. To this end, the ramp 48 includes an elongatelower ramp portion 60 and an upper ramp portion 62 extending from a topside of the lower ramp portion 60. The lower ramp portion 60 is angledfrom the sidewall 34 so as to define the tapering of the interior space42 towards the bottom wall 36. The upper ramp portion 62 is configuredto overlie a portion of the rear sidewall 34 and be connected therewith(such as by a fastener 64 or some other similar connecting device) toretain the ramp 48 in position within the supply container 14. Theoutlet port 26 extends through the upper ramp portion 62 and isconfigured to extend through the rear sidewall 34 as well so that thehose 28 can be connected into communication with the pump conduit 52.

The lower ramp portion 60 extends across substantially an entire widthof the interior space 42 and thereby divides the interior space 42 froman equipment receptacle 66 located behind the ramp 48. The equipmentreceptacle 66 is a recessed space located within the footprint of thesupply container 14 and provides a convenient space outside the interiorspace 42 for mounting pump equipment 68 used to generate flow of pellets70 (shown in phantom in FIG. 4) from the inlet 54 and through the pumpconduit 52. The pump equipment 68 may include one or more solenoids 72for controlling flow of pressurized air into the pump conduit 52 at aventuri pump housing 74 disposed adjacent to the inlet 54 and within theinterior space 42. The pump equipment 68 may also include controlelectronics and other known components typically used with pneumaticfill pumps, and this equipment may be modified in other embodimentswithout departing from the scope of the current invention.

With reference to FIGS. 5 and 6, the venturi pump housing 74 of the pump50 is shown in further detail. The venturi pump housing 74 includes aportion of the pump conduit 52 running along an elongate direction ofthe venturi pump housing 74, the elongate direction being defined from afirst end 80 of the housing 74 adjacent to the inlet 54 and a second end82 of the housing 74 opposite the first end 80. As well understood inventuri-type pumps, additional flow passages (not shown in FIGS. 5 and6) deliver pressurized air from the solenoids 72 into the pump conduit52 so as to cause a pressure gradient in the pump conduit 52, thepressure gradient tending to draw pellets 70 into the pump conduit 52for driving with the pressurized air. In the exemplary embodiment shown,the venturi pump housing 74 also includes a front surface 84 facing awayfrom the ramp 48 when installed, a rear surface 86 abutting the ramp 48when installed, and a pair of light apertures 88 extending through thehousing 74 from the rear surface 86 to the front surface 84. The lightapertures 88 are separate and independent from the pump conduit 52 andadditional flow passages carrying air through the pump 50. The lightapertures 88 are configured to receive the indicator device, whichincludes LEDs 22 as described briefly above.

As most clearly shown in FIG. 6, the LEDs 22 of the indicator device aremounted at least partially within the light apertures 88 so that theLEDs 22 are substantially flush with or slightly projecting beyond thefront surface 84 of the venturi pump housing 74. As a result, the LEDs22 are mounted or incorporated in structure already present within theinterior space 42 of the supply container 14. In addition, the LEDs 22advantageously do not significantly increase the resistance to flow ofpellets 70 towards the bottom wall 36, as caused by gravity. Therefore,the indicator device does not adversely affect the flow of pellets 70within the interior space 42. In the mounting position shown in FIG. 6,the wiring (not shown) for powering and controlling the LEDs 22 mayextend through the remainder of the light aperture 88 and into theequipment receptacle 66 for connection to such a power supply. The LEDs22 and light apertures 88 are shown to be positioned about halfwaybetween the first and second ends 80, 82, but this positioning may bemodified to be closer to one or the other end 80, 82 in otherembodiments. It will also be understood that the LEDs 22 may be mountedin other positions in or out of the venturi pump housing 74, includingbut not limited to being recessed within the light apertures 88, inother embodiments consistent with the invention. Several of thesealternatives are described with reference to FIGS. 7 and 8 below.

In the illustrated embodiment, the LEDs 22 are rugged LEDs that areresistant to high temperatures and other environmental conditionsnormally present within the supply container 14. These rugged LEDs maybe similar to those used in taillights or light bars of modern emergencyvehicles. Although LEDs 22 are shown in the exemplary embodiment, theindicator device could include other types of light sources, such asincandescent light sources mounted within the light apertures 88, inother embodiments. Furthermore, the light sources could be positionedaway from the venturi pump housing 74 and connected to the lightapertures 88 via optical cables that transmit emitted light energy intothe light apertures 88 from the light sources. Regardless of the type oflight chosen for use as the indicator device, additional hardwareassociated with the light sources may also be positioned at or insidethe venturi pump housing 74. For example, in some embodiments thecontroller 24 and/or any associated hardware operating as a driver forthe light sources may also be positioned adjacent to or at leastpartially within the housing 74. Consequently, the LEDs 22 or otherlight sources define a minimized profile that does not significantlyaffect or interfere with the placement and operation of other componentsof the fill system 12, whether these components are located behind theramp 48 in the equipment receptacle 66 or within the interior space 42.

In operation, the LEDs 22 of the indicator device emit light energy intothe interior space 42 of the supply container 14. This light energy isblocked from transmission into the interior space 42 when the level ofpellets 70 in the supply container 14 is high enough to cover the LEDs22. When the level of pellets 70 drops during use, the LEDs 22 becomepartially uncovered and then completely uncovered as the level ofpellets 70 approaches an empty condition. This uncovering of the LEDs 22causes the light energy emitted from the LEDs 22 to be emittedthroughout the entire interior space 42 to internally illuminate amajority of the supply container 14. In this regard, the light energybecomes a visual indication corresponding to the supply container 14approaching the empty condition. In other embodiments, the LEDs 22 maybe actuated to illuminate only when the level of pellets 70 reaches athreshold that approaches the empty condition. The LEDs 22 in such anarrangement could be located in other positions in the supply container14, including but not limited to at the lid 40 where dust and adhesivepellets 70 cannot affect the transmission of light energy into theinterior space 42. Additionally, the light energy emitted by the LEDs 22may be routed directly to the window 46 rather than being emittedthroughout the entire interior space 42 in some embodiments.

The positioning of the LEDs 22 within the interior space 42 is tailoredto provide the initial visual indication at a time when the supplycontainer 14 requires refill, but with sufficient time for an operatorto see the visual indication and cause the refill to happen in advanceof reaching the completely empty condition. For example, the LEDs 22 maybe positioned within the supply container 14 such that the LEDs 22 areuncovered by the pellets 70 when the pellets 70 have emptied to aselected fill percentage within the range of about 2% filled to about25% filled. More preferably, the pellets 70 will uncover the LEDs 22 ata selected fill percentage within the range of about 2% filled to about10% filled. This selected fill percentage for uncovering the LEDs 22should provide the visual indication for a sufficient period of time tocause a refill of the supply container 14 before the supply container 14becomes completely empty. In addition, an operator can determineimmediately from the outside environment whether a supply container 14requires refill by looking through the windows 46 to see if light energyis being emitted in the interior space 42. As a result, periodic checkson the fill level by opening the lid 40 of the supply container 14 areno longer necessary, and the operator of the adhesive dispensing system10 can be reasonably assured of preventing the supply container 14 fromrunning out of pellets 70. The melter 16 and other downstream componentsof the adhesive dispensing system 10 can therefore be operatedsubstantially continuously without lengthy delays caused by refillingthe supply container 14.

The visual indication provided by the indicator device can be enhancedor modified in a number of ways. In one example, the LEDs 22 areoperated to provide light energy in an intermittent flashing patternrather than a solid pattern. The flashing light energy will be initiallydetectable within the interior space 42 as a pulsing light emergingthrough the pellets 70 when the LEDs 22 are nearly uncovered. Thispulsing light will later be detected as a flashing light energy when theLEDs 22 are completely uncovered. In this way, the indicator device candraw more attention to the supply container 14 approaching the emptycondition so that the empty condition can be avoided. In anotherexample, the ramp 48 is painted so as to be a color contrasting to oneor both of the pellets 70 or the light energy emitted by the LEDs 22.This contrasting color is chosen to be more readily visible through thewindows 46. Thus, regardless of whether the light energy is emitted assolid light or as flashing light, the high contrast provided by thecolor of the ramp 48 will enhance the likelihood that the visualindication will be seen by an operator of the adhesive dispensing system10. More particularly, the visibility of the visual indication isincreased by one or more of these modifications.

With reference to FIG. 7, another alternative for enhancing the visualindication provided by the indicator device is shown. In thisembodiment, the venturi pump housing 100 has been modified to include aseries of light apertures 102 a, 102 b, 102 c, 102 d, 102 e locatedalong the elongate length of the housing 100 between the first andsecond ends 80, 82. In all other respects, the venturi pump housing 100of this embodiment is identical to the venturi pump housing 74 of thefirst described embodiment, and the same reference numbers have beenused on identical components and surfaces where appropriate withoutfurther explanation. By providing LEDs 22 in each of the series of lightapertures 102 a-e, the intensity of light energy emitted throughout theinterior space 42 may be increased multiple times as the supplycontainer 14 approaches the empty condition. The intensity increases asthe level of pellets 70 is lowered because the pellets 70 sequentiallyuncover new pairs of LEDs 22 when approaching the empty condition. Tothis end, when the level of pellets 70 is approaching the first end 80of the housing 100 near the inlet 54, the intensity of light energyemitted in the interior space 42 and through the windows 46 issignificantly increased compared to when the level of pellets 70 is atthe second end 82 of the housing 100. Accordingly, a more critical needfor an immediate refill of the supply container 14 draws more attentionwith a more intense visual indication.

The LEDs 22 shown in FIG. 7 or other embodiments may also be oriented indifferent directions such that light energy emitted by the LEDs 22 ismore likely to spread quickly throughout the entire interior space 42when the supply container 14 approaches the empty condition. This variedpositioning of the LEDs 22 also helps ensure that an uneven pile ofpellets 70 within the interior space 42 does not adversely affect theamount of time provided by the visual indication to refill the supplycontainer 14. The LEDs 22 shown in FIG. 7 may also be divided intomultiple portions of LEDs 22 defining different intensities or colors oflight emitted by the LEDs 22. For example, a first portion of the LEDs22 in the light apertures 102 a, 102 b may emit light energy at a firstcolor or intensity, and a second portion of the LEDs 22 in the lightapertures 102 c, 102 d, 102 e may emit light energy at a second color orintensity. The second portion of the LEDs 22 is uncovered after thefirst portion, and the modified color or intensity of light energyemitted by the second portion of the LEDs 22 causes a change in thevisual indication provided within the interior space 42 and through thewindows 46. To this end, an operator may be able to determine differentlevels of reaction based on the type of visual indication provided. Whenonly the first color or intensity of light is emitted, the operator willunderstand that refill is necessary but the empty condition is notimminent. When the second color or intensity of light is emitted, theoperator will understand that refill needs to happen promptly becausethe empty condition is imminent. It will be appreciated that the numberof LEDs 22 in each portion may be modified without departing from thescope of the invention.

With reference to FIG. 8, another alternative arrangement for theindicator device is shown. More specifically, FIG. 8 illustrates asimilar side view, as shown in FIG. 4 of the first embodiment describedabove. Alternatively or in addition to providing a LED 22 within a lightaperture 88 in the venturi pump housing 74, the indicator device of thisembodiment may include a LED 22 a coupled to the lower ramp portion 60of the ramp 48 and/or a LED 22 b positioned immediately behind a rampaperture 110 located in the lower ramp portion 60 of the ramp 48. Aswith the previous embodiments, the LEDs 22 a, 22 b are rugged LEDs thatare resistant to high temperatures and other environmental conditionsnormally present within the supply container 14. The LED 22 a coupled tothe ramp 48 is located within the interior space 42 and within the flowpath of the pellets 70 of adhesive, so the LED 22 a is designed with aminimized profile to limit the additional resistance to the flow ofpellets 70 towards the bottom wall 36 and the inlet 54. The LED 22 bpositioned behind a ramp aperture 110 in the ramp 48 is located withinthe equipment receptacle 66 and so is out of the flow path of thepellets 70 in the interior space 42. However, the light energy emittedby the LED 22 b is directed through the ramp aperture 110 and into theinterior space 42 for use in the same manner as the other LEDs 22, 22 adescribed above. The ramp aperture 110 may include a transparent windowblocking communication between the interior space 42 and the equipmentreceptacle 66, or the ramp aperture 110 may be open in some embodiments.It will be appreciated that one or more of the LEDs 22, 22 a, 22 b andmounting arrangements described in the various embodiments may beprovided individually or in any combination according to the preferencesof the end user.

With reference to FIGS. 9 through 11, the generalized method ofoperation for the fill system 12 is shown. In these Figures, the LED 22is shown mounted on the ramp 48 which guides the pellets 70 towards thebottom wall 36. No other structure in the interior space 42 or in theequipment receptacle 66 is shown in detail. As shown in FIG. 9, thesupply container 14 is filled with a high amount of pellets 70 such thatthe supply container 14 is not approaching the empty condition. In thisstate, the level of pellets 70 in the interior space 42 covers up theLED 22 to such an extent that effectively none of the light energy(shown schematically by wave lines 120) escapes through the pellets 70and into the portion of the interior space 42 where that light energycould be detected through the windows 46. Therefore, no visualindication is provided to refill the supply container 14 in thisoperational state of the fill system 12.

When the level of pellet fill within the supply container 14 is reducedto an intermediate level as shown in FIG. 10, the pellets 70 may stillsubstantially cover the LED 22. However, the amount of pellets 70located on top of the LED 22 is reduced to the extent that a smallamount of the light energy 120 emitted by the LED 22 escapes through thepellets 70 into the remainder of the interior space 42. For example, inthe embodiments where a flashing light energy is emitted by the LED 22,this small amount of light energy 120 may be detected through thewindows 46 as a soft pulsing light signal. As will be readilyunderstood, as the level of pellets 70 drops lower, the amount of lightenergy 120 escaping through the pellets 70 will increase, therebyincreasing the intensity of the visual indication corresponding to thesupply container 14 approaching the empty condition.

Finally, the level of pellet fill within the supply container 14 willeventually be reduced to the low level shown in FIG. 11. In thisoperational state, the pellets 70 no longer cover the LED 22. As aresult, the light energy 120 is largely transmitted throughout theinterior space 42 and through the windows 46 for detection by anoperator of the fill system 12. Consequently, the visual indication isprovided at a maximum intensity when the level of pellets 70 within theinterior space 42 falls below the threshold set by the location of theLED 22. When this visual indication is detected, a refill of the supplycontainer 14 may be performed, which will return the supply container 14back to the state of FIG. 9, in which no visual indication is visible inthe interior space 42 or through the windows 46. As noted above, thethreshold at which the visual indication is provided may be modified tofit the needs of the end user (e.g., a more frequently monitored fillsystem 12 can provide the visual indication at a lower level of fillbecause the refill will be actuated promptly upon emission of the visualindication).

Consequently, the LEDs 22, 22 a, 22 b of the indicator devices that areprovided in the supply containers 14 according to the invention operateto emit a visual indication when the supply container 14 approaches anempty condition. In this regard, operators of a fill system 12 includingthe supply container 14 may be notified of an imminent empty conditionwell enough in advance to allow for refilling of the supply container 14prior to the interior space 42 becoming completely empty. Thus, systemdowntime for refilling the supply of material is minimized for a melter16 and other components of an adhesive dispensing system 10 using thefill system 12. Furthermore, the indicator device is a passive devicethat operates effectively to provide the visual indication without theneed for complex or expensive level sensors in some embodiments.Therefore, the fill system 12 of the current invention includes areliable mechanism for indicating an imminent empty condition withoutadding significant complexity or expense to the manufacture andmaintenance of the fill system 12. The reduced downtime enabled by useof this fill system 12 makes the fill system 12 beneficial forapplications in all filling technologies, whether related to adhesivedispensing or otherwise.

While the present invention has been illustrated by a description ofseveral embodiments, and while such embodiments have been described inconsiderable detail, there is no intention to restrict, or in any waylimit, the scope of the appended claims to such detail. Additionaladvantages and modifications will readily appear to those skilled in theart. Therefore, the invention in its broadest aspects is not limited tothe specific details shown and described. The various features disclosedherein may be used in any combination necessary or desired for aparticular application. Consequently, departures may be made from thedetails described herein without departing from the spirit and scope ofthe claims which follow. What is claimed is:

1. A fill system configured to supply particulate adhesive to anadhesive dispensing system, comprising: a supply container including aninterior space for receiving the particulate adhesive and defined by atleast one sidewall and a bottom, the at least one sidewall including atleast a portion defined by translucent or transparent material; and anindicator device for emitting a visual indication when the supplycontainer is approaching an empty condition, the indicator deviceincluding at least one light source communicating with the interiorspace such that light energy is emitted in the interior space so as tobe visible through the translucent or transparent material to anoperator when the supply container is approaching the empty condition.2. The fill system of claim 1, wherein the supply container furtherincludes a window defined by the translucent or transparent material atthe sidewall, and the light energy emitted by the light source isvisible through the window when the supply container is approaching theempty condition.
 3. The fill system of claim 1, wherein the light sourceemits light energy throughout the interior space such that a majority ofthe supply container is internally illuminated when the supply containeris approaching the empty condition.
 4. The fill system of claim 1,wherein the light source is mounted at least partially in additionalstructures located within the interior space such that the light sourceprovides minimized resistance to gravity-driven flow of particulateadhesive towards the bottom of the interior space.
 5. The fill system ofclaim 4, further comprising: a pump including a venturi pump housing andconfigured to selectively remove particulate adhesive from the interiorspace, the light source being mounted at least partially within theventuri pump housing.
 6. The fill system of claim 1, wherein theindicator device includes a plurality of light sources that arepositioned to emit light energy in different directions within theinterior space.
 7. The fill system of claim 1, wherein the light sourceis a rugged light emitting diode resistant to high temperatures.
 8. Thefill system of claim 1, wherein the supply container further includes aramp configured to direct gravity-driven flow of particulate adhesivewithin the interior space towards the bottom, and the light source ismounted on or adjacent to the ramp such that the light sourcecommunicates with the interior space proximate the bottom, the lightsource being uncovered when the supply container approaches the emptycondition.
 9. The fill system of claim 8, wherein the ramp is paintedwith a color contrasting to the particulate adhesive or to the lightenergy emitted by the light source, thereby further increasingvisibility of the visual indication.
 10. The fill system of claim 8,wherein the light source is coupled to the ramp so as to be locatedwithin the interior space of the supply container.
 11. The fill systemof claim 8, wherein the ramp includes at least one ramp aperture and thelight source is positioned behind the ramp and adjacent to the rampaperture such that light energy is emitted through the ramp apertureinto the interior space.
 12. The fill system of claim 8, wherein theindicator device includes a plurality of light sources positioned in aseries along an elongate length of the ramp such that the series oflight sources is sequentially uncovered as the supply containerapproaches the empty condition.
 13. The fill system of claim 8, whereinthe indicator device includes at least a first portion of light sourcesand a second portion of light sources that emits light energy at adifferent intensity or color than the first portion, and the secondportion of light sources is positioned so that the second portion oflight sources is uncovered after the first portion of light sources isuncovered to thereby change the visual indication when the supplycontainer approaches the empty condition.
 14. The fill system of claim8, wherein the light source emits light energy in a flashing pattern sothat the light energy emitted in the interior space may be initiallydetected as a pulsing of light energy through the particulate adhesivewhen the light source is nearly uncovered, and then detected as aflashing light energy when the light source is uncovered.
 15. The fillsystem of claim 1, wherein the light source is positioned within thesupply container such that the light source is uncovered when theparticulate adhesive in the interior space has emptied to a selectedfill percentage within the range of about 2% filled to about 25% filled.16. The fill system of claim 1, wherein the fill system is configured toperform a method of supplying particulate adhesive to an adhesivedispensing system, the method comprising: receiving particulate adhesivewithin an interior space of the supply container; removing particulateadhesive from the interior space of the supply container to supply theparticulate adhesive to the adhesive dispensing system; and illuminatingthe light source such that light energy is emitted by the light sourcein the interior space so as to be visible through the translucent ortransparent material to an operator when the supply container isapproaching the empty condition.
 17. A method of supplying particulateadhesive to an adhesive dispensing system using a fill system includinga supply container having at least one sidewall with at least a portiondefined by translucent or transparent material and including anindicator device having a light source, the method comprising: receivingparticulate adhesive within an interior space of the supply container;removing particulate adhesive from the interior space of the supplycontainer to supply the particulate adhesive to the adhesive dispensingsystem; and illuminating the light source such that light energy isemitted by the light source in the interior space so as to be visiblethrough the translucent or transparent material to an operator when thesupply container is approaching the empty condition.
 18. The method ofclaim 17, wherein the supply container includes a window defined by thetranslucent or transparent material, and the method further comprises:emitting the light energy from the light source through the window whenthe supply container is approaching the empty condition, therebyproviding a visual indication detectable outside the supply container.19. The method of claim 17, wherein illuminating the light sourcefurther comprises: flashing the light source intermittently such thatthe light energy emitted in the interior space may be initially detectedas a pulsing of light energy through the particulate adhesive when thelight source is nearly uncovered, and then detected as a flashing lightenergy when the light source is uncovered.
 20. The method of claim 17,wherein the indicator device includes a plurality of light sourcespositioned in a series, and the method further comprises: uncovering theseries of light sources in a sequential manner as the particulateadhesive is removed and as the supply container approaches the emptycondition.
 21. The method of claim 17, wherein the indicator deviceincludes at least a first portion of light sources and a second portionof light sources that emits light energy at a different intensity orcolor than the first portion, and the method further comprises:uncovering the first portion of light sources to emit a first lightenergy in the interior space; and uncovering the second portion of lightsources to emit a second light energy having a different intensity orcolor that the first light energy in the interior space.
 22. The methodof claim 17, wherein the indicator device includes a plurality of lightsources positioned in different orientations, and the method furthercomprises: illuminating the plurality of light sources such that lightenergy is emitted in different directions throughout the interior space,thereby illuminating a majority of the supply container when the supplycontainer is approaching the empty condition.
 23. The method of claim17, further comprising: utilizing the fill system of claim 1 to receiveparticulate adhesive, remove particulate adhesive to supply the adhesivedispensing system, and illuminate the light source when the supplycontainer is approaching an empty condition.